diff --git a/tools/aconfig/aconfig_storage_file/protos/aconfig_storage_metadata.proto b/tools/aconfig/aconfig_storage_file/protos/aconfig_storage_metadata.proto
index 7de43ca918..f6bf1a43c4 100644
--- a/tools/aconfig/aconfig_storage_file/protos/aconfig_storage_metadata.proto
+++ b/tools/aconfig/aconfig_storage_file/protos/aconfig_storage_metadata.proto
@@ -28,7 +28,8 @@ message storage_file_info {
   optional string flag_val = 5;
   optional string flag_info = 6;
   optional string local_overrides = 7;
-  optional int64 timestamp = 8;
+  optional string default_flag_val = 8;
+  optional int64 timestamp = 9;
 }
 
 message storage_files {
diff --git a/tools/aconfig/aconfig_storage_read_api/include/aconfig_storage/aconfig_storage_read_api.hpp b/tools/aconfig/aconfig_storage_read_api/include/aconfig_storage/aconfig_storage_read_api.hpp
index b8ee06a590..e6d75373a9 100644
--- a/tools/aconfig/aconfig_storage_read_api/include/aconfig_storage/aconfig_storage_read_api.hpp
+++ b/tools/aconfig/aconfig_storage_read_api/include/aconfig_storage/aconfig_storage_read_api.hpp
@@ -41,7 +41,7 @@ enum FlagInfoBit {
 struct MappedStorageFile {
   void* file_ptr;
   size_t file_size;
-  ~MappedStorageFile();
+  virtual ~MappedStorageFile();
 };
 
 /// Package read context query result
diff --git a/tools/aconfig/aconfig_storage_write_api/aconfig_storage_write_api.cpp b/tools/aconfig/aconfig_storage_write_api/aconfig_storage_write_api.cpp
index 197486d246..f529f7954c 100644
--- a/tools/aconfig/aconfig_storage_write_api/aconfig_storage_write_api.cpp
+++ b/tools/aconfig/aconfig_storage_write_api/aconfig_storage_write_api.cpp
@@ -17,11 +17,6 @@ using namespace android::base;
 
 namespace aconfig_storage {
 
-/// destructor
-MutableMappedStorageFile::~MutableMappedStorageFile() {
-  munmap(file_ptr, file_size);
-}
-
 /// Map a storage file
 Result<MutableMappedStorageFile*> map_mutable_storage_file(std::string const& file) {
   struct stat file_stat;
diff --git a/tools/aconfig/aconfig_storage_write_api/include/aconfig_storage/aconfig_storage_write_api.hpp b/tools/aconfig/aconfig_storage_write_api/include/aconfig_storage/aconfig_storage_write_api.hpp
index 1eca1e0cda..ff06cbc6de 100644
--- a/tools/aconfig/aconfig_storage_write_api/include/aconfig_storage/aconfig_storage_write_api.hpp
+++ b/tools/aconfig/aconfig_storage_write_api/include/aconfig_storage/aconfig_storage_write_api.hpp
@@ -11,11 +11,7 @@ using namespace android::base;
 namespace aconfig_storage {
 
 /// Mapped flag value file
-struct MutableMappedStorageFile{
-  void* file_ptr;
-  size_t file_size;
-  ~MutableMappedStorageFile();
-};
+struct MutableMappedStorageFile : MappedStorageFile {};
 
 /// Map a storage file
 Result<MutableMappedStorageFile*> map_mutable_storage_file(
diff --git a/tools/aconfig/aconfig_storage_write_api/tests/storage_write_api_test.cpp b/tools/aconfig/aconfig_storage_write_api/tests/storage_write_api_test.cpp
index aeede49306..54373798c9 100644
--- a/tools/aconfig/aconfig_storage_write_api/tests/storage_write_api_test.cpp
+++ b/tools/aconfig/aconfig_storage_write_api/tests/storage_write_api_test.cpp
@@ -80,13 +80,10 @@ TEST_F(AconfigStorageTest, test_boolean_flag_value_update) {
   ASSERT_TRUE(mapped_file_result.ok());
   auto mapped_file = std::unique_ptr<api::MutableMappedStorageFile>(*mapped_file_result);
 
-  auto ro_mapped_file = api::MappedStorageFile();
-  ro_mapped_file.file_ptr = mapped_file->file_ptr;
-  ro_mapped_file.file_size = mapped_file->file_size;
   for (int offset = 0; offset < 8; ++offset) {
     auto update_result = api::set_boolean_flag_value(*mapped_file, offset, true);
     ASSERT_TRUE(update_result.ok());
-    auto value = api::get_boolean_flag_value(ro_mapped_file, offset);
+    auto value = api::get_boolean_flag_value(*mapped_file, offset);
     ASSERT_TRUE(value.ok());
     ASSERT_TRUE(*value);
   }
@@ -97,7 +94,6 @@ TEST_F(AconfigStorageTest, test_invalid_boolean_flag_value_update) {
   auto mapped_file_result = api::map_mutable_storage_file(flag_val);
   ASSERT_TRUE(mapped_file_result.ok());
   auto mapped_file = std::unique_ptr<api::MutableMappedStorageFile>(*mapped_file_result);
-
   auto update_result = api::set_boolean_flag_value(*mapped_file, 8, true);
   ASSERT_FALSE(update_result.ok());
   ASSERT_EQ(update_result.error().message(),
@@ -110,16 +106,12 @@ TEST_F(AconfigStorageTest, test_flag_has_server_override_update) {
   ASSERT_TRUE(mapped_file_result.ok());
   auto mapped_file = std::unique_ptr<api::MutableMappedStorageFile>(*mapped_file_result);
 
-  auto ro_mapped_file = api::MappedStorageFile();
-  ro_mapped_file.file_ptr = mapped_file->file_ptr;
-  ro_mapped_file.file_size = mapped_file->file_size;
-
   for (int offset = 0; offset < 8; ++offset) {
     auto update_result = api::set_flag_has_server_override(
         *mapped_file, api::FlagValueType::Boolean, offset, true);
     ASSERT_TRUE(update_result.ok()) << update_result.error();
     auto attribute = api::get_flag_attribute(
-        ro_mapped_file, api::FlagValueType::Boolean, offset);
+        *mapped_file, api::FlagValueType::Boolean, offset);
     ASSERT_TRUE(attribute.ok());
     ASSERT_TRUE(*attribute & api::FlagInfoBit::HasServerOverride);
 
@@ -127,7 +119,7 @@ TEST_F(AconfigStorageTest, test_flag_has_server_override_update) {
         *mapped_file, api::FlagValueType::Boolean, offset, false);
     ASSERT_TRUE(update_result.ok());
     attribute = api::get_flag_attribute(
-        ro_mapped_file, api::FlagValueType::Boolean, offset);
+        *mapped_file, api::FlagValueType::Boolean, offset);
     ASSERT_TRUE(attribute.ok());
     ASSERT_FALSE(*attribute & api::FlagInfoBit::HasServerOverride);
   }
@@ -139,16 +131,12 @@ TEST_F(AconfigStorageTest, test_flag_has_local_override_update) {
   ASSERT_TRUE(mapped_file_result.ok());
   auto mapped_file = std::unique_ptr<api::MutableMappedStorageFile>(*mapped_file_result);
 
-  auto ro_mapped_file = api::MappedStorageFile();
-  ro_mapped_file.file_ptr = mapped_file->file_ptr;
-  ro_mapped_file.file_size = mapped_file->file_size;
-
   for (int offset = 0; offset < 8; ++offset) {
     auto update_result = api::set_flag_has_local_override(
         *mapped_file, api::FlagValueType::Boolean, offset, true);
     ASSERT_TRUE(update_result.ok());
     auto attribute = api::get_flag_attribute(
-        ro_mapped_file, api::FlagValueType::Boolean, offset);
+        *mapped_file, api::FlagValueType::Boolean, offset);
     ASSERT_TRUE(attribute.ok());
     ASSERT_TRUE(*attribute & api::FlagInfoBit::HasLocalOverride);
 
@@ -156,7 +144,7 @@ TEST_F(AconfigStorageTest, test_flag_has_local_override_update) {
         *mapped_file, api::FlagValueType::Boolean, offset, false);
     ASSERT_TRUE(update_result.ok());
     attribute = api::get_flag_attribute(
-        ro_mapped_file, api::FlagValueType::Boolean, offset);
+        *mapped_file, api::FlagValueType::Boolean, offset);
     ASSERT_TRUE(attribute.ok());
     ASSERT_FALSE(*attribute & api::FlagInfoBit::HasLocalOverride);
   }